Engine cleaner compositions are known to remove carbonaceous and lacquer deposits from air and fuel handling surfaces within internal combustion engines without the need to disassemble the engine. Throttle plates, intake manifolds, injectors, intake valves and combustion chambers all are prone to becoming coated by deposits that can affect the power, efficiency, and driveability of the vehicle. Deposits usually form, for example, when partially oxidized fuel backs up from combustion chambers when the engine is run and then shut off. Vapors and mists are deposited as liquids that may crosslink to form lacquers and then bake to form carbonaceous deposits during subsequent operation of the engine.
Prior art techniques for engine cleaning include, for example, the following.
(a) Pouring an engine cleaner composition directly into an open air throttle on the carburetor with the engine operating at high rpm. In this procedure, the cleaner is mixed with the fuel and the mixture burned during the combustion process.
(b) An injector cleaning process involving the use of a pressurized container containing an engine fuel and cleaning agent. The pressurized container is connected to a transfer apparatus which is then adapted to the fuel rail of the engine. The fuel system is disabled and the engine is operated on the fuel/cleaner mixture from the pressurized container.
(c) A vacuum disconnect technique which involves disconnecting a vacuum line from a vacuum port in communication with the air intake manifold and then connecting a rubber flex line to the vacuum port. The other end of the flex line is inserted into a container of the cleaning fluid. The engine is started and the vacuum used to evacuate the cleaning fluid from the container into the vacuum port.
(d) Do-it-yourself engine cleaning compositions that can be added directly to the fuel tank of a vehicle with the cleaning taking place during routine operation of the vehicle""s engine.
In order to efficiently and effectively clean an engine of the deposits typically present, an engine cleaner composition having a wide solubility range is highly desirable. Typical solvent blends, for example, provide solubility over only a narrow range dictated by the overall composition of the blend. One way in which a wide solubility range can be provided is in the form of a microemulsion. Microemulsion engine cleaners include a water (polar) phase and an oil (non-polar) phase and, therefore, provide a composition effective to dissolve and/or remove a wide range of engine deposits. One commercially available microemulsion engine cleaner is available under the trade designation xe2x80x9c3M FUEL SYSTEM CLEANERxe2x80x9d from Minnesota Mining and Manufacturing Company (St. Paul, Minn.). Although microemulsions may provide the desired wide range of solubility they are typically quite expensive to manufacture. In view of the foregoing, an engine cleaner composition providing a wide range of solubility of engine deposits is highly desirable.
The present invention provides engine cleaner compositions comprising:
a single phase solution comprising:
(i) a polar solvent having a Hildebrand solubility parameter of about 10 cal1/2 cmxe2x88x923/2 or greater;
(ii) a non-polar solvent, immiscible with the polar solvent, having a Hildebrand solubility parameter of about 10 cal1/2 cmxe2x88x923/2 or less; and
(iii) a fugitive cosolvent having a higher evaporation rate than the polar solvent and the non-polar solvent.
In a preferred embodiment of the engine cleaner composition the polar solvent has a Hildebrand solubility parameter of about 12 cal1/2 cmxe2x88x923/2 or greater, more preferably about 14 cal1/2 cmxe2x88x923/2 or greater. Preferred polar solvents are selected from the group consisting of water, triethanolamine, ethanolamine, ethyleneglycol, diethyleneglycol, nitromethane, n-methylpyrolidone, pyridine, morpholine, and dimethylsulfoxide. In a preferred embodiment the polar solvent is present in the engine cleaner composition in an amount ranging from about 5% to about 80% by weight, more preferably about 10 to about 50% by weight.
In a preferred embodiment of the engine cleaner composition the non-polar solvent has a Hildebrand solubility parameter ranging from about 8 to 10 cal1/2 cmxe2x88x923/2. Preferred non-polar solvents are aromatic. Preferred non-polar solvents are selected from the group consisting of toluene, xylene, and aromatic petroleum distillates. A particularly preferred non-polar solvent is naphthalene depleted aromatic petroleum distillate.
The polar and non-polar solvents comprising the engine cleaner composition are immiscible with one another. As used herein the term xe2x80x9cimmisciblexe2x80x9d means that when mixed together in approximately equal proportions the polar and non-polar solvent form two discrete phases. The phases may be identified, for example, by the formation of an interfacial meniscus between the phases. Immiscible as used herein is not meant to be absolute since immiscible polar and non-polar solvents may exhibit some degree of partial miscibility.
Engine cleaner compositions of the present invention further comprise a cosolvent which acts to solubilize the polar solvent and the non-polar solvent such that a single phase solution is formed. The cosolvent is xe2x80x9cfugitivexe2x80x9d meaning that it has a higher volatility than either the polar solvent or the non-polar solvent. In a preferred embodiment the cosolvent has an evaporation rate that is greater than about 1 (relative to butyl acetate), more preferably greater than about 2 (relative to butyl acetate). Preferably, the polar and non-polar solvents have an evaporation rate that is less than about 0.5 (relative to butyl acetate) more preferably less than about 0.1 (relative to butyl acetate). Preferred cosolvents are selected from the group consisting of isopropyl alcohol, ethanol, and n-propanol. In a preferred embodiment the cosolvent is present in the engine cleaner composition in a range from about 5% to about 80% by weight, more preferably 20% to about 60% by weight, and most preferably about 35% to about 65% by weight.
The polar and non-polar solvent may also be characterized according to their xcex4P which is derived from Hansen solubility parameter components according to the equation:
xcex4P=(xcex4p2+xcex4h2)1/2
where:
xcex4p=Hansen polar component, and
xcex4h=Hansen hydrogen bonding component.
According to this method preferred polar solvents have a xcex4P of about 4.0 or greater, more preferably about 5.5 or greater, and most preferably about 7.0 or greater. Preferred non-polar solvents have a xcex4P ranging from about 0 to about 3, more preferably ranging from about 1 to about 2.
In a preferred embodiment, the engine cleaner composition is provided in a pressure resistant container under the pressure of an aerosol propellant.
In a preferred embodiment, the engine cleaner composition further includes a non-fugitive cosolvent such as propylene glycol monomethylether.
In a preferred embodiment the engine cleaner composition further includes a detergent such as oleic acid saponified with triethanolamine.
The present invention also provides a fluid-dispensing device attachable to an air-intake system of an internal combustion engine for introducing an engine cleaner composition into the air intake system, the fluid-dispensing device comprising:
(i) a pressure-resistant container having a reservoir and a discharge orifice, the reservoir charged with an engine cleaner composition and a propellant;
(ii) a shutoff valve having an inlet and an outlet, the inlet connected with the discharge orifice of the pressure-resistant container for receiving engine cleaner composition discharged from the container; and
(iii) a length of flexible tubing having an inlet end and an outlet end and a central bore extending from the inlet end to the outlet end, the inlet end of the tubing connected with the outlet of the valve for receiving engine cleaner composition discharged from the pressure-resistant container through the valve;
wherein the fluid-dispensing device provides a flow rate of engine cleaner composition at the outlet end of the length of flexible tubing ranging from about 25 to about 50 grams per minute.
In another embodiment, the present invention provides a fluid-dispensing device attachable to an air-intake system of an internal combustion engine for introducing an engine cleaner composition into the air intake system, the fluid-dispensing device comprising:
(i) a container having a reservoir and a discharge orifice, the container charged with an engine cleaner composition;
(ii) a length of flexible tubing having an inlet end and an outlet end and a central bore extending from the inlet end to the outlet end, the inlet end of the length of flexible tubing in communication with the reservoir of the container for receiving engine cleaner composition from the reservoir; and
(iii) an adapter having an inlet end and an outlet end, the inlet end connected with the outlet end of the flexible tubing and the outlet end adapted to be connected to the air intake plenum for dispensing engine cleaner composition into the plenum;
wherein the fluid-dispensing device when connected to the air intake plenum of an internal combustion engine providing a vacuum ranging from about 18 to about 22 in of Hg provides a flow rate of engine cleaner composition ranging from about 25 to about 50 grams per minute.
The present invention also provides a method of cleaning an internal combustion engine having a vacuum port in communication with an air intake manifold, the method comprising the steps of:
(a) providing a fluid-dispensing device as described above;
(b) connecting the fluid-dispensing device to the vacuum port; and
(c) operating the internal combustion engine to generate a vacuum at the vacuum port thereby causing the engine cleaning composition to be drawn from the reservoir through the tubing and into the air intake manifold of the internal combustion engine.
In another embodiment the present invention provides a method of cleaning an internal combustion engine having an air intake manifold, the method comprising the steps of:
(a) providing a fluid-dispensing device as described above;
(b) inserting the outlet end of the flexible tubing into the air intake manifold of the internal combustion engine;
(c) operating the internal combustion engine; and
(d) opening the on-off valve to allow engine cleaner composition to flow under pressure of the aerosol propellant from the reservoir through the tubing and into the air intake manifold of the internal combustion engine.